In a wireless communication system such as a WiFi system, information is transmitted and received in orthogonal frequency-division multiplexing (OFDM) packets. A receiver in such a system needs to detect a packet and its format first, and then the receiver configures its hardware and software to receive and decode the data portion of the packet.
Each OFDM packet includes a plurality of pre-amble fields to assist the receiver in detecting, synchronizing, and conditioning the packet. The pre-amble fields are followed by an encoded signal field that carries information about data rate, packet length, modulation and encoding type. The signal field is decoded and then used to configure the receiver to receive and decode the data portion of the packet. In the high throughput (HT) WiFi standard IEEE draft document (802.11n), mixed mode and green field OFDM frame formats are allowed to co-exist with a low throughput legacy frame format. In this standard the mixed mode frame format allows a legacy device to handle an HT packet properly and the green field frame format allows for less overhead and therefore higher throughput in an HT only system.
Accordingly, what is desired is a system and method that allows a receiver to receive and decode data packets in an efficient fashion when the receiver can receive packets in different types of formats. The system and method should be easily implemented, cost effective and adaptable to existing communications systems. The present invention addresses such a need.